1. Field of the Invention
The present invention relates to a torque converter comprising a pump rotor, a turbine rotor that can be driven by the pump rotor and a stator, the turbine rotor being firmly connected to a transmission input shaft so as to rotate with it, the transmission input shaft forming an axial duct with an initial region and a final region for a hydraulic fluid.
2. Description of the Related Art
A torque converter of this type is disclosed, for example, by DE 41 21 586 A1 corresponding to U.S. Pat. No. 5,215,273, or DE 195 40 294 A1, corresponding to U.S. Pat. No. 5,950,483.
In torque converters, the axial duct is generally formed as a central bore. In order to connect the central bore to a feed opening, radial bores are introduced into the transmission input shaft in the initial region, via which bores the central bore is connected to a feed opening for the hydraulic fluid. In practice, it has transpired that, in individual cases, stress cracks can occur in the transmission input shaft in the region of the radial bores.